Builders are desirable ingredients in powdered detergent formulations, which optimize the effectiveness of surfactants by sequestering calcium, magnesium and other `hardness` ions present in the wash water that adversely affect detergency.
The manner in which detergent builders improve the cleaning powers of detergent compositions is related to a combination of factors such as emulsification of soil particles, solubilization of water insoluble materials, promotion of soil suspension in the wash water so as to retard soil redeposition, sequestration of metallic ions, and the like.
Phosphates, such as tripolyphosphates and pyrophosphates, are widely used as builders due to their excellent ability to sequester `hardness` ions. However, the effect of phosphates upon the eutrophication of lakes and streams has been questioned and their use in detergent compositions has been subject to government scrutiny and regulation. Alternatives for phosphates are widely used by detergent formulators as builders in detergent formulations. Compositions and materials change frequently as formulators attempt to improve cleaning performance while offering greater convenience in handling at lower material cost. The industry has made substantial efforts to find suitable substitutes for phosphates, however, all have one or more drawbacks that offset their value in the formulations
French Patent Specification 2,612,521 to Bernard Brosse discloses selected chelating polymers similar to those of the invention.
U.S. Pat. Nos. 3,711,458, and 3,835,109 to Olofson disclose processes for peptide synthesis employing a vinyloxy carbonyl group as a protecting group.
U.S. Pat. No. 3,923,742 to Haschke discloses a process for producing a polycarboxylate phosphate substitute said to be readily biodegradable.
U.S. Pat. No. 4,559,159 to Denzinger et al. discloses water soluble copolymers for use with detergents.
While polymeric carboxylates have been found to be suitable builders, few have been found to be biodegradable, indeed, few synthetic polymers have been found to be biodegradable. One method of improving the biodegradability of synthetic polymers has been to incorporate hydrolyzable linkages within the main polymer backbone. This approach, however, usually does not produce high molecular weight polymers. A second method of improving biodegradability is a method of this invention to couple relatively small biodegradable carboxylates to a polymer backbone which will, through hydrolyzable linkages, break down to form polyvinyl alcohol (PVA) or a PVA-like copolymer. Upon hydrolysis, the components are then expected to be biodegradable.
The polymeric builders herein described contain carbamate linkages with environmentally acceptable amino acids. While not wishing to be bound by theory, it is theorized that the carbamate linkages will break down in the environment to polyvinyl alcohol and the corresponding amino acid, both of which are reported be be relatively environmentally acceptable. Further, the electrostatic and site specific charge interactions of the compounds of this invention contribute to the builder efficiency.
Accordingly, it is an object of the present invention to provide a novel class of effective `hardness` ion sequestering agents which may be employed in detergent compositions as a replacement, in whole or in part, for phosphate builders.
A further object of the present invention is to provide detergent compositions employing these effective, non-phosphate builders.
Yet another object is to improve the biodegradability of selected polymers.